Induction meter



H. FRHLICH June 30, 1931.

mnucmou METER Filed April 17. 192a IN VEN TOR MSKGR Patented June 30, 1931 UNITED STATES PATENT OFFICE HANS FRHLICH OF ZUG, SWITZERLAND, ASSIGNOR T LANDIS & GYR, A-G. A J'OINT- STOCK COMPANY OF SWITZER-LAND IN DUC'IION METER Application filed April 17, 1928, Serial N0. 270,667, a11d in Switzerland April 27, 1927.

The invention relates t0 induction me-;ers and more particularly t0 nowel and useful improvements in dev'ices fo1 preventing, 001- recting or minimizing errors arising 01113 0'f circuit conditions o1 changes.

Objects and advantages 0f the invention Will be sei; forth in art hereinafter und in part Will be obvious herefrom, 0r 1nay be learned by practice with ehe invention, the same being realized and attained by means 01: the instrumentalities and combinations pointed out in the appended elaims.

The invention consists in the nove1 parts, construction, arrangements, combinations and improvements herein shown und described.

The accompanying drawings, referred t0 herein and constituting a part hereof, illustrate one embodiment of the invention, und together with the description, serve t0 explain the prineiples 0f the invention.

Of the drawings:

Fig. 1 shows an elevation 0f a meter mechanisn1 embodying the invention, certain parts being shown somewhat diagrannnat ically;

Fig. 2 is a curve showing the relation between the normal current t01que, und the torque produced by the use 0f applicants invention;

Fig. 3 is a vect0r diagram 0f the fluxes of a conveneional induction meter; and

Fig. 4 is a vector diagrarn of the fluxes 01 a typical meter in accordance with the present invention.

In the embodied und present prefer1red form 01": the invention, a meter disc 1 is fixed 0n a. spindle 2, whieh is journaled at its ende in bearings 4 und 5, which are fixed 011 the meter frarne 6. A W01n1 7, 01' other suitable device is carried 011 the spindle 2 t0 drive a register 0r like mechanism.

The pressure magnet may be of various fonns und as embodied comprises a th1eearmed core 10, having a pressure coil 11 wound upon the central arm 12 0f the core. The 0ther arme 13 und 14 extend from the back reach of the core 10, 0n either side 0f the coil, to 1onn p01e pieces adjacent t0 the disc. The current magnet likewise may be 01? w=rious f01'1ns, and as embodied is located on the opposite side of the meter disc from ehe pressure 1nagnet, und comprises a U-shaped c0re 19 hzwing its two arms 20 and 21 exending toward the disc 1 t0 constitute p0]e pieces. Cu1rent coils 22 are wound upon the anns 0f the c0re in any suitable 01 convenient way.

A nmgnetic shunt p1ate 01' membe1 26, usually 0f iron, is arranged across the poles 0f the current magnet and may be varied in form f01 different forms 0f current 1nag net 01' as may be otherwise found desirable. On the eurrenu c0re a ring 27 0f electrically condueting muterial is c2uried und this is pxreferably arranged 011 0ne arm of the 0111- rent c0re behind the c0il winding, as shown in the drawings.

In Figure 2, the curve A represents the driving torque 0f a conventional inductien 1neter plotted against current strength expressed as percentage of full 10ad und dis1e garding the bmking aetiun 01 the current flux on the meter disc. This curve also represents the resnltant torqne acting 011 the n1eter disc in {L meter e1nbodying the present improvements. Curve B represents the driving torque 01 {L meter according t0 the presentinvention in which the torque is slightly in excess 01 us1ml torque so as t0 provide the necessury excess torque to overc01ne the braking acti0n due to the current flux.

The driving torque 01 an induction n1eter is usually proportional t0 the cu1rent strength in the series c0ils, but the current flux normally produces a braking acti0n 011 the meter disc which braking action increases with the loading 0f the meter und reduces the registration of the meter. Mag- Eli) netic shunts fr the se1ies magnet increase the torque und compensate f01 the bmking effect 0f the current flux, but thisn1agnetic shunt disturbs the phasedisplacement adjustment of the meter, thereby introducing an er1or which is compensated for by means 0f an electrically conducting ring surrounding an arm 0f the current core, such as ring 27. Figure 3 is a vector diagram and shows the driving.current fluxes (pm and (u 01"? a meter in exact phase opposition, one of these fluxes passing upwardly through the disc, the other downwardly, und with0ut the use 0f the' conducting ring. After ring 27 has been applied to the series core, there results a phase displacement of the flux as shown in Figure 4, thereby producing asupplemental currenttorque as represented by the VCC'O1 diagrrn, Figure' 4. This cu1rent torque varis as the square 0I" the current, but does not depend 011 the power-factor.

In a typical construction according t0 my inve'ntion, the supplemental t-orque p10 duced by the Jring 27 is about 2% 0'f Ehe mai n currnt torque at 100% 01. load und i1nity power factor.

The shunt platte 26 with an inductive load causes a dr0p in the characteristic perform anee curve. This drop, however, is Compensated f01' by the arrangement of the electrically conducting ring 27. This ring causes a lead in the current, which with an inductive m1 acts more powerfully than with a purely ohmic load. By this 1neans, the result can be obtained that the Characceristic performance curves are similar for all kinds ofload andare thus practically eliminable.

The invention in its broader aspects is not limited t0 the specific mechanisms shown and described butdepartures may bo nmde therefrorn within thescope of the accom panying claims without deparuing f101n the principles of the invention und withont sacrificing its chief advantages.

What I claim is 1. An induction meter including a meter disc und driving mechanism therefor including a driving coil and c0re, a magnetic shunt plate cooperating with pole pieces 0.f the c0re and a single ring 0f electrically c0nducting material encircling said c0re 0n the opposite side 0f the C011 fr0m Said shunt plate.

2. An induction 1neter including a n1ete1 disc and driving' mechanisrn thereforincluding a pressure c0il and c0re, a series 0011 and core 011 the opposite side 0f the disc fron'1 the pressure magnet, a magnetic shunt plate bstween the p01e pieces of the Series magnet und the meter disc, und a ring of electrically conducting material encircling the current core on the opposite side 0f the c0il from said magnetic shunt plate.

'3. An induction meter including in comb1nat1on a meter d1sc and dr1V1ng mechan1s1n therefor 111clud1ng a series 00i1 ancl core, a magnetic shunt plate between the In testi1nony whereof, -I have signed my nenne to this specifi(zation.

HANS FROHLICH. 

